My friend have a buick special -58 that we have tried to fix the main brake cylinder on. We replaced the "piston" and gaskets and made a hening/grinding (don't really know the english word) of the cylinder to get rid of rust and scratches. This all took about a year because of other things coming in the way... So when we finally had got it together again and had put out the air the brakes worked just fine! But as you press the pedal it won't go up itself after you have taken the foot of it. How is it supposed to go up? Can we have missed some part or what have we done wrong? Regards Eddie Landmer